Structural,
microstructural and dielectric properties of transition metal doped, i.e., Co
and Fe (0, 1, 3 and 5 mol% each) SnO2 and the formation of their
nanorods by Ce (4 mol%) co-doping have been studied. These nanoparticles and
nanorods were fabricated by a chemical route using polyvinyl alcohol as
surfactant. The X-ray diffraction patterns show that all the specimens have tetragonal
rutile structure without any extra phase. The transmission electron microscopy
analysis shows that the average particle size lies in the range 11-30 nm and
the diameter of rods in the range 5-20 nm and length 50-200 nm. It is observed
that by co-doping of Ce3+, the resulting nanoparticles assembled
themselves into rod like structures. The nature and concentration of dopants
are found to play crucial role in tuning the morphology and electrical
properties of nanostructures. The
dielectric behaviour of Co and Fe dopedand Ce co-doped SnO2 nanostructures
has been analyzed and it is observed that the value of dielectric constant (εr)
decreases rapidly in lower frequency regime, whereas it depicts a slight
dispersion in the middle and higher frequency range and resonant behaviour in
sufficiently higher frequency region. The frequency dependent ac conductivity
shows higher resistivity of nanoparticles and explains the dispersion in
dielectric behaviour.

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